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Aug 30, 2023 at 17:10 comment added Boris @ David E Speyer Thank you very much for your kind help.
Aug 30, 2023 at 17:03 comment added David E Speyer But the more general question of understanding what $G_0(X)$ DOES look like in this case seems worthwhile, so I'm not leaving an answer on the assumption that someone else will answer that question.
Aug 30, 2023 at 17:02 comment added David E Speyer To the specific question about $e_1$, $e_2$, $(0,b,c)$, no. Consider the cone with rays $(1,1,-1)$, $(1,-1,1)$, $(-1,1,1)$. For any two of these rays $\rho$ and $\sigma$, the point $(1/2) (\rho+\sigma)$ is in $\mathbb{Z}^3$ but not an integer combination of $\rho$ and $\sigma$. So no $GL_3(\mathbb{Z})$ matrix can transform $\rho$ and $\sigma$ to $e_1$ and $e_2$.
Aug 30, 2023 at 15:52 history asked Boris CC BY-SA 4.0